The methodologies employed in health and health services research depend heavily upon the sample survey as a source of data. The expense, lack of precision, and time-consuming nature of this approach are accepted in lieu of alternatives. With the emergence of a computer technology that can manipulate very large data-bases, new sources of data are available. The massive investment for administrative data processing in the health care delivery programs (Medicare and Medicaid) can be exploited for health services research. This proposal links large administrative data-files to investigate a specific topic: the descriptive epidemiology of psychotropic drug prescribing in large, heterogeneous, defined populations of children and prescribing physicians. The estimated 2 million prescriptions for the 200,000 children eligible for Tennessee Medicaid benefits over the 5-year period 1973-1978 will be reviewed. The analysis for children will encompass prescription incidence rates and utilization ratios, frequent use of psychotropic drugs, exposure to multiple agents, doctor shopping, and 5-year trends. Physician training and characteristics of current practice will be correlated with prescribing of psychotropic drugs. The association of the mal-prescribing of antiinfectives with increased prescribing of psychotropic drugs will be tested. This research will supply currently unavailable data for policy purposes. It has implications for improving quality and lowering cost of government-provided medical care for children, improving physician prescribing practices and the development of health services research technology.